Sprinter 4WD Conversion Idea, GMT-800 IFS.

[Len.Barron]

this method also is much more flexible for someone who wants to customize some aspects of it...for instance, incorporating a differential drop or repowering with a different engine would be much easier with individual pieces vs a formed piece that sets those positions/elevations...it's not really that much welding anyways..

 

[luthj]

I have needed to make a few adjustments (this is a prototype after all), and having more separate pieces made this a bit easier. If I was going to do a run of 50? Yeah, I would cut the part count considerably.

 

[Sharkfox]

I gave it a fair bit of thought. If I had access to a press break I would have done that. But the reality is that for a handful of runs, spread over a few years, the extra cost doesn't make sense. Especially since this is DIY. I guess most shops would charge an arm and a leg to setup and break such a small number of varied parts.

I suppose since you are doing the welding, it makes financial sense. In our shop, forming is much faster and cheaper than welding and some laser time is offset due to eliminating some edges cut. Just curious. Tab and slot is tried and true. Looking forward to more progress!

 

[luthj]

Getting down to business with the last of the fitups.








Initially the shock body and the shaft were interfering. The lower shock bracket has an offset. Normally offset forward, but that wasn't working. I swapped them left to right so the offset was backwards, and everything fits. Its tight at full droop, but it clears. This is the passenger side. Since I widened the track a bit to clear the frame rails, I was expecting to need CV spacers. Then I offset the diff to the driver side. At full droop the bearings in the inner CV are about 1/2-3/4" outside the cup (when in the upper position). So I need to get some 1-3/4" spacers I think. I will double check with my OEM CV axles, just in case this aftermarket ones are a bit shorter. The passenger side will likely need a 1/2" spacer.



Here is the rack to diff clearance. I think I can fit a 1/4" spacer to get a bit better ackerman, and still clear the diff. Note that the upper boss in this photo has been ground down about 1/4" already. As an aside, removing the diff with the subframe installed may not be possible. it may require lowering the subframe about 2-3" so there is enough clearance to rotate the pinion end into its bracket. I haven't taken a look at the racks hard lines yet. Might end up needed to make a new set to clear the diff.

 

[shade]

Do you think you'll need different CV boots? I've seen these used when the ribs rub too much, leading to excessive wear.

05+ Tacoma, 10+ 4Runner and 07-14 FJ Cruiser High Angle Outer CV Boot Kit

05+ Tacoma, 10+ 4Runner and 07-14 FJ Cruiser High Angle Outer CV Boot Kit

allprooffroad.com

 

[Len.Barron]

Getting down to business with the last of the fitups.








Initially the shock body and the shaft were interfering. The lower shock bracket has an offset. Normally offset forward, but that wasn't working. I swapped them left to right so the offset was backwards, and everything fits. Its tight at full droop, but it clears. This is the passenger side. Since I widened the track a bit to clear the frame rails, I was expecting to need CV spacers. Then I offset the diff to the driver side. At full droop the bearings in the inner CV are about 1/2-3/4" outside the cup (when in the upper position). So I need to get some 1-3/4" spacers I think. I will double check with my OEM CV axles, just in case this aftermarket ones are a bit shorter. The passenger side will likely need a 1/2" spacer.



Here is the rack to diff clearance. I think I can fit a 1/4" spacer to get a bit better ackerman, and still clear the diff. Note that the upper boss in this photo has been ground down about 1/4" already. As an aside, removing the diff with the subframe installed may not be possible. it may require lowering the subframe about 2-3" so there is enough clearance to rotate the pinion end into its bracket. I haven't taken a look at the racks hard lines yet. Might end up needed to make a new set to clear the diff.

have you cycled it when turned at full lock both directions?

 

[luthj]

have you cycled it when turned at full lock both directions?

Yes. GM did good with their alignment, and the axis passes perfectly through the outer CV, so the axle does not displace with steering input.

 

[luthj]

I pulled the boot off to confirm the plunge depth. Looks like I only need 1/2" to get the bearing inside the cup. Its good to see copious moly grease in side as well. I discovered the outer boot on this axle is nicked, and will need to be replaced. I will just pull the 15 year old boot off the use GM axle. Its still in perfect shape.

IMG_20191207_130340564 by J Luth, on Flickr

I verified the steering shaft placement in the engine compartment. It is within 1/4" of the original, which should do the job. I also double checked the engine mount placement against the van, and its plus/minus 1/8". I am very confident it should bolt up with only minor adjustment. I also measured the wheel wells for clearance cutting. About a 3x3" wedge needs to be cut from the strut upper brace. This should leave a nice flat area to weld a right angle bracket to. I will then pass a bolt into the subframes upper shock tower plate, for maximum strength.

IMG_20191207_132319891 by J Luth, on Flickr


The lines fit, but the clearance is tight. I want to move the rack closer, so I will see if I can bend the lines to route over top instead of behind. It should work, assuming I don't kink them.

 

[luthj]

Do you think you'll need different CV boots? I've seen these used when the ribs rub too much, leading to excessive wear.

05+ Tacoma, 10+ 4Runner and 07-14 FJ Cruiser High Angle Outer CV Boot Kit

05+ Tacoma, 10+ 4Runner and 07-14 FJ Cruiser High Angle Outer CV Boot Kit

allprooffroad.com

Since I am going with factory-ish geometry, I am hoping I don't need them. The outer CV boot is a thermoplastic (not rubber/neoprene), and is very abrasion resistant. I will take a closer look, but I don't think the folds were rubbing at ride height.

 

[luthj]

Getting the last few bits welded on.







Working on the sway bar mounting. May need to do a little trimming. For some reason the OE sway bar bushings were too small, and I can't find an OE bushing for the 800s with 36mm OD. The 900 bushing fits, but I need to figure out the amount of compression it needs for a tight fit.

 

[luthj]

Sway bar mounted. The only welding/fab work left on the subframe is the UCA shims. Looks like I will need 3/16" shim on the rear, and 1/4" on the front bushing.

 

[shade]

I hope you're going to knock the edges and corners down on the sub-frame with a flap disc before paint. That'll save some skin down the road eventually.

 

[luthj]

Yeah, lots of prep before paint. Not looking forward to it...

 

[shade]

Yeah, lots of prep before paint. Not looking forward to it...

I actually enjoy deburring and generally cleaning up parts, but it's one of those things like house painting or buffing floors - either you like it or it's a PITA.

Some better-than-HF flap wheels and flap discs spun by some decent tools should make quick work or those parts. Since this isn't the bad old days and you're probably not going to be doing it outside, wear a respirator. And hearing protection. And eye protection. And good gloves. And you'll probably want to wear some coveralls so you can peel 'em off before coming inside.

Ok, so it's going to be a little PITA.

 

[luthj]

I definitely have a bucket for my work clothes by the door. That raw steel smell is pervasive.

The only major annoyance is all the nooks and crannies, I need to get some 1" grinding disks and a compact right angle tool. I also need to scrub and wash the weld grime off, and of course this thing weighs 140lbs, ha! Maybe I should just find someone to hot dip galvanize it for me...

I got this amazing deal on 40 grit thin flap disks on amazon, 25 of them for 26$, I am going to need them all! Those laser cut edges are rough on the disks.